Method of manufacturing a continuous stringer for a sliding clasp fastener

ABSTRACT

In manufacturing a continuous slide fastener stringer, a plastic wire is coiled into a helix abut a fixed mandrel, and the helix is withdrawn from the mandrel while its convolutions are braked on one side so that the helix is distorted. It is thereafter shaped on a heated spacing wheel, and each convolution is deformed by a toothed kinking disc. The stringer so formed has convolutions of periodically varying inclination and has alternating parallel shanks connected by inclined portions retaining the original coiling pitch and having protuberances which secure loops of sewing threads by means of which the stringer is attached to a supporting tape.

United States Patent Popovitsch 1 May 30, 1972 54] METHOD OFMANUFACTURING A 3,197,537 7/1965 Hansen ...l8/19 c x A 3,337,672 8/1967Stemgrubner ..264/28| SLIDING CLASP FASTENER FORElGN PATENTS ORAPPLlCATlONS [72] Inventor: Ernst Popovitsch, Stuttgart-Steckfeld, Ger-1,080,321 8/1967 Great Britain .264/DlG. 40

many Primary Examiner-Robert F. White [73] Assignec: Dr. Karl F. NageleFeinmaschinenbau, Assistant Examine, Richm-d Shear stuttgart'HohenheiniGermany Attorney-Kelman and Berman 22 F] d: A 30, 197 1 l e pr 0 57ABSTRACT [21 1 Appl' NOJ 33469 In manufacturing a continuous slidefastener stringer, a plastic wire is coiled into a helix abut a fixedmandrel, and the helix is [30] Foreign Application Priorit D tawithdrawn from the mandrel while its convolutions are braked on one sideso that the helix is distorted. It is thereafter shaped y 2, 1969Germany 19 22 605-2 on a heated spacing wheel, and each convolution isdeformed by a toothed kinking disc. The stringer so formed has convolu-I 40 tions of periodically varying inclination and has alternating [51]Int. Cl. ..B29c 17/02 parallel shanks connected by inclined portionsretaining the [58] Field of Search ..264/28 1 320, DIG. 40; 18/12,original coiling pitch and having protuberances which secure 18/19 Cloops of sewing threads by means of which the stringer is attached to asupporting tape. 56 f t 1 Re erences Cl ed 5 Claims, 8 Drawing FiguresUNITED STATES PATENTS 3,077,001 2/1963 Yoshida ..18/19 C Patented May30, 1972 3 Sheets-Sheet 1 INVENTOR: Ernsf P0/J0W f d1 BY: Wm M KimPatented May 30, 1972 3 Sheets-Sheet 2 INVENTOR: Ems? pafiom' sa BY: W0M 3% Patented May 30, 1972 3 Sheets-Sheet 5 METHOD OF MANUFACTURING ACONTINUOUS STRINGER FOR A SLIDING CLASP FASTENER The present inventionrelates to a method of manufacturing a continuous stringer for a slidingclasp fastener from a shaped strand of a plastics material coiled into ahelix, which has a periodically varying angle of inclination, beingcoiled continuously on a fixed mandrel and subsequently withdrawntherefrom.

The construction of such a stringer, which comprises a plurality offastener elements joined by interconnecting portions and made from afilament that is basically coiled, preferably into the shape of a helix,necessitates a particularly strong deformation, which exceeds the amountat present usual for making such stringers.

It is known to manufacture sliding clasp fastener stringers from aplastics material in the shape of deformed helices in such a mannerthat, after coiling the material into a helix having an approximatelyregular angle of inclination, the parts of the stringer adjacent thecoupling surfaces formed thereon can be made approximately withoutinclination by the insertion of curved cylinders, cams, or profiled andheated wheels so that the connections between the individual couplingelements of the stringer, i.e. the inclined parts or portions, arelocated in the rearward area of the helix facing the coupling surfaces.Should, however, the inclined parts which connect the coupling elementstogether not run in the rearward region of the helix actually inclinedto its longitudinal axis, but in the central area of the elements, i.e.between the front and rear reverse turn of the profiled strand, theknown deformation measures are not sufficient for economic manufacture.More particularly, it was not possible, with the hitherto known methodsand apparatus for deforming stringers, to construct theseinterconnecting parts so that they extend from loop to loopapproximately parallel to the longitudinal axis of the row of elementsin the form of cross-pieces.

It is an object of the present invention to bring about by simple means,a particularly strong deformation of a helix into a closed shape,preferably of the described configuration. It is a further object tobring about, also by simple means, the withdrawal of the coiled plasticsstrand from a fixed mandrel and, at the same time, to preform thestringer.

The invention consists, therefore, in a method of manufacturing acontinuous sliding clasp fastener stringer from a shaped strand of asuitable plastics material coiled into a helix, which has a periodicallyvarying angle of inclination, being coiled continuously on a fixedmandrel and subsequently withdrawn therefrom, wherein, in the withdrawalzone, the convolutions are braked at one side and withdrawn at the otherside in the area of a cross-sectional reduction of the mandrel and arepreformed during formation of the individual elements and theelement-interconnecting portions retaining the convolution spacing, theamount of the decrease in crosssection at one side correspondingapproximately to the longitudinal distortion of the stringer elements,and wherein the stringer is fed after the free end of the mandrel into aheated shaping wheel having peripheral recesses to receive the elementsand also pins engageable therein, the helix being permanently deformedby means of at least one toothed disc operable on the inclinedconnecting portions, said connecting portions being applied against saidpins of the shaping wheel I by said toothed disc or discs in such amanner that the completed connecting portions run approximately parallelto the longitudinal axis of the stringer.

Preferably, the stringer is initially coiled into a helix by means of athread guide rotatable about the fixed mandrel and said mandrel issecured in a magnetically heated coiling head. Furthermore, the stringeris provided with coupling surfaces in the area of the preforming toothedwheels by means of an intermittently operable stamping die.

Advantageously, at the lagging supported bent positions of the inclinedportions, there is formed a protuberance projecting towards the support.

In order that the invention may be more clearly understood, referencewill now be made to the accompanying drawings which show certain aspectsthereof by way of example, and in which:

FIG. 1 shows a side view of a complete apparatus,

FIG. 2 shows a side view of a part of the apparatus being used forwithdrawing the helically shaped stringer for deforming and stamping,part of the apparatus being removed to make the showing clearer,

FIG. 3 shows a section through the stamping device along the line IIlIIIof FIG. 2,

FIG. 4 shows a plan view of part of the apparatus according to FIG. 2,

FIGS. 5 and 6 show cross-sections through various parts of the coilingmandrel,

FIG. 7 shows a section along the line VII-VII of FIG. 8 made at rightangles to the axis of rotation through the periphery, shown indevelopment of the heated shaping wheel having a toothed wheel inengagement therewith, and

FIG. 8 shows a section along the line VIII-VIII of FIG. 7.

Referring now the drawings, a shaped strand 1 of a suitablethermoplastic material is drawn off a feed spool 2 and fed into amagnetically heated winding head 3, in a stationary part 5 of which issecured a coiling mandrel 6. The plastics filament 1 is fed through arotating ring 4 of the winding head 3 and wound into a helix about thefixed winding mandrel 6. The convolutions thrust themselves forward andarrive between preforming wheels 7 and 8 (FIG. 4). These latter areperipherally provided with transverse gaps 9 at predetermined intervalsdepending upon the desired spacing of the fastener elements. A gap isprovided between the preforming wheels 7 and 8 which corresponds only tothe width of the coiling mandrel 6 at its end 6b which is tapered. Thus,the tapered end 6b of the mandrel is supported from opposite sides,while the coil passes through and the arrangement ensures a diametricalpressure on the convolutions thus assisting in forming coupling surfaces14, as the helix passes between the wheels.

The effective stamping of the coupling surfaces 14, however, alsonecessitates a stamping die 15 (FIGS. 1 and 2). An adjustable backingblock 16 which covers considerably more windings than the stamp die 15,supports the stamping pressure and also the mandrel at 6b. By adjustingthe backing block 16 by means of an eccentric disc 17, the height of thecoupling surfaces 14 can be adjusted to any desired degree. Since thecoupling surface 14 is stamped before the fixing operation, i.e. beforethe helix enters into a heated wheel or drum 18, the amount of materialwhich is needed for the inclined portion 11 or 19 connecting thefastener elements have to be taken into account during the stampingoperation. This extra material is made available during winding, due tothe cross-sectional shape of the thicker part 6a of the mandrel. Themandrel is tapered at 6b to a decreased cross-section in the receptionarea of the preforming wheels 7 and 8. An annular groove 10 in thepreforming wheel 8 offers room for the connecting portion 11 (FIG. 2) asyet lying at an oblique angle. A resilient pointed braking member 23presses the convolutions of the helix 12 in the direction of thepreforming wheel 8, so that they are engaged first by the preformingwheel 8. By this arrangement, moreover, the convolution is slightlyoflset so that its diametrical portion facing the preforming wheel 7 canengage therein more efficiently and without error.

The preforming so achieved, with the obliquely inclined portions 11, isnot permanent since the material can still spring back.

The end 6b of the winding mandrel leads tangentially into the heatedshaping wheel or drum 18. This latter consists of discs 18a, 18b and(FIG. 8). The disc 18a is provided with cross-pieces 20 whose distancefrom one another corresponds exactly to the desired spacing of theelements in the finished fastener. The cross-pieces 20 are of the sameheight as the stringer. The disc 180 has pins 21, which correspond tothe spacing of the disc 18a, but are only as high as the inclinedportions 19 of the stringer allow. The base of an annular groove 22formed between the discs 18a and 18c is formed by the peripheral surfaceof the central disc 18b. This groove receives the end 6b of the mandreland also the coupling surfaces 14. It also ofiers space for the stripper24.

The ultimate shape and direction of the connecting portions IQ isachieved in the heated shaping wheel 18. To this end, toothed discs 25and 26 are arranged on the periphery of the heating wheel 18. Theselatter have teeth 27, which run synchronously with the pins 21. Theinclined portion 19 is formed and directed between the teeth 27 and thepins 21. Slightly inclined surfaces 28 on the pins 21 effect formationof a protuberance 29 on the inclined portions 19 of the stringer. Thislatter offers the advantage that when loading the stringer sewn to itscarrier tape, the seam cannot slip. The protuberance 29 is also used foranchoring the sewing thread.

An exact shape and direction of the inclined portion 19 connecting theelements can best be achieved by re-rolling, by means of additionaltoothed discs similar to 25, 26, one behind the other. The shape of theteeth 27 then differs from disc to disc. The teeth 27 of the first disc25 are slender and pointed and those of the last one 26 rather blunt.

The stringer is withdrawn from the heated wheel by means of a stripper24. At the exit point, the stringer is initially cooled by a stream ofair, ensuring the correct spacing of the elements of the stringer.Complete cooling of the stringer is effected in the open air. It isadvantageous to apply a slight stress by a light roller 30 for thispurpose, so that twisting is avoided as far as possible. In order todecrease or remove the twist on a finished fastener, it is advisable tocoil one stringer of the fastener, for example, to the right and theother to the left.

It has proven advantageous to double up the machines side by side, forwhich purpose a stringer closing device 31 is provided at the end of themachines to draw both the produced stringers together to form acompleted chain. This has the advantage that complete cooling off canresult in the closed position of the two cooperating strings and thetensions within the stringers compensate each other. The finished chainis either wound on a spooling member 32 under slight stress or the chaincan be fed back into a container from which it is removed for sewing onto the tapes. All movable parts of the machine are driven by anadjustable motor and run in synchronism.

What we claim is:

l. A method of manufacturing a continuous sliding clasp fastenerstringer from a shaped strand of plastics material which comprises:

a. continuously coiling said strand on a fixed elongated mandrel to forma helix having a plurality of convolutions,

1. said mandrel having a terminal portion of reduced cross sectiondefining a withdrawing zone;

b. applying force longitudinally of said mandrel to one part of eachconvolution in said withdrawing zone;

0. simultaneously applying force to another part of said convolution tobrake said withdrawing,

1. said forces being sufiicient to withdraw said convolutions from saidmandrel and to deform each convolution into a first portion having agreater angle of inclination and a second portion having a smaller angleof convolution, said second portions being interconnected by said firstportions,

2. whereby said helix is given a periodically varying angle ofinclination and constitutes an elongated stringer, said second portionsconstituting stringer elements;

d. feeding said stringer from said mandrel to a heated spacing wheel,

1. said wheel having a plurality of peripheral recesses respectivelyreceiving said elements and a plurality of pins; and

e. engaging each of said first portions between a tooth of a tootheddisc and a pin of said wheel under a pressure sufficient to bend saidfirst portion substantially parallel to the longitudinal axis of saidstringer. 2. A met od as set forth in claim 1, wherein said strand lScoiled on said mandrel by passing the strand through a thread guidewhile said thread guide rotates about said mandrel and said mandrel issecured in a heated coiling head.

3. A method as set forth in claim 1, wherein said second portions ofsaid convolutions are engaged by a reciprocating stamping die with aforce sufficient to form a coupling surface on each second portion priorto said withdrawing.

4. A method as set forth in claim 3, wherein said plastic material isthermoplastic, and said stringer is being cooled after said engaging ofeach of said first portions between said tooth and said pin.

5. A method as set forth in claim 4, wherein said pressure is sufficientto form a protuberance on said first portion.

2. whereby said helix is given a periodically varying angle ofinclination and constitutes an elongated stringer, said second portionsconstituting stringer elements; d. feeding said stringer from saidmandrel to a heated spacing wheel,
 2. A method as set forth in claim 1,wherein said strand is coiled on said mandrel by passing the strandthrough a thread guide while said thread guide rotates about saidmandrel and said mandrel is secured in a heated coiling head.
 3. Amethod as set forth in claim 1, wherein said second portions of saidconvolutions are engaged by a reciprocating stamping die with a forcesufficient to form a coupling surface on each second portion prior tosaid withdrawing.
 4. A method as set forth in claim 3, wherein saidplastic material is thermoplastic, and said stringer is being cooledafter said engaging of each of said first portions between said toothand said pin.
 5. A method as set forth in claim 4, wherein said pressureis sufficient to form a protuberance on said first portion.